1. Field of the Invention
The present invention relates to driving force control apparatus and method for an automotive vehicle in which a vehicular target driving force which is in accordance with a vehicle driver""s demand is derived and the derived target driving force is realized by controlling an actual driving force in a vehicular drive system from an engine to driven wheels.
2. Description of the Related Art
A Japanese Patent Application First Publication No. Heisei 11-78620 published on Mar. 23, 1999 (which corresponds to a U.S. Pat. No. 6,148,257 issued on Nov. 14, 2000) exemplifies a previously proposed driving force control apparatus. In the above-described Japanese Patent Application First Publication, such a technique that a target driving force is derived according to a map retrieval based on an accelerator manipulated variable and a vehicular velocity.
However, as will be described later, in the above-described vehicular driving force control apparatus disclosed in the Japanese Patent Application First Publication Heisei 11-78620, it is impossible to establish a compatibility between a vehicular acceleration performance from a standstill and overtake acceleration performance.
First, suppose a relationship between an accelerator manipulation method of a vehicle driver (in other words, a model pattern in which the vehicle driver depresses an accelerator pedal during an acceleration start of the vehicle) and the target driving force. In an acceleration scene (when the driver has decided that the vehicle should be accelerated), the driver manipulates the accelerator depression (depresses deeply the accelerator pedal), and, thereafter, maintains a position of accelerator pedal so that an accelerator manipulation variable is constant. Then, when the vehicular velocity reaches to a certain value, the driver satisfies the acceleration and carries out an accelerator pedal release operation (to zero the manipulated variable of the accelerator). A locus of the target driving force in this acceleration scene is such that the target driving force is once increased substantially vertically in response to the first accelerator pedal deep depression. Then, when the subsequent accelerator manipulated variable is maintained constant, the target driving force is gradually decreased along with an increase in a vehicular velocity due to the acceleration. Thereafter, an accelerator return (or accelerator pedal release) operation is carried out so that a vehicular state is converged into a vicinity to a certain vehicular velocity.
Next, suppose that the overtake acceleration is carried out with accelerator manipulated variable equal to the acceleration start described above. In this case, since the target driving force characteristic is prepared so as to be converged to a certain vehicle velocity, an extra accelerator manipulated variable is less, the vehicle state is resulted in the convergence into a certain vehicular velocity without accelerator return (accelerator pedal release) operation.
In this case, it cannot be thought that a sufficient degree of acceleration is carried out, with a fact that the driver generally depresses more deeply the accelerator pedal than usual and, thereafter, carries out the return operation for the accelerator pedal during the vehicular acceleration taken into consideration. To obtain the sufficient overtake acceleration, the driver depresses the accelerator pedal more deeply than the case of the acceleration start (the accelerator manipulated variable is increased). Then, an additional driving force is added to the target driving force and an accelerator feeling becomes satisfactory.
However, to achieve this addition of the target driving force, the target driving force characteristic with respect to accelerator manipulated variable is not present so as to substantially be translate to an adjacent target driving force line the cannot be prepared due to an overshooting feeling during the acceleration start. Because it is necessary to create the target driving force characteristic with respect to the accelerator manipulated variable in such a way that the target driving force characteristic converges into a driving force corresponding to a running resistance at a certain vehicular velocity.
If not so, the target driving force characteristic would not be competed with the running resistance and a vehicular characteristic is indicated such that the acceleration is increased continuously without stop for a long period of tine if the return manipulation of the accelerator is carried out. Hence, a control easiness to maintain the vehicular velocity and a cruise-speed running characteristic are worsened. In addition, in terms of the acceleration feeling, the driver expects that the vehicle acceleration becomes soon settled. Hence, such an evaluation is not always carried out that the acceleration feeling is preferable.
To solve the above-described inconsistency, such many discussion as, in an overtake acceleration region, the cruise speed running state and the acceleration state are divided according to a detection of the vehicle driver""s acceleration demand and an appropriate driving force characteristic is given to the divided cruise run state and acceleration state have been made. In this method, it is necessary to grasp strictly the vehicle driver""s acceleration demand. However, this is very difficult. With a risk considered when an erroneous determination is made, a sufficient correction cannot be made. Hence, if possible, it is desirable to provide no system in which a switching occurs in response to some trigger.
A plurality of proposals have been made in which the same driving force control is achieved through a gear shift diagram control of a transmission. However, many problems are provided in points listed below to perform the conformity to the acceleration feeling. 1) With a multiple-ratio geared transmission as a prerequisite, a driving force step difference is always present as a result of control and a smoothness becomes sacrificed. 2) Even if a continuously variable transmission is used, a revolution change is always necessary. In a case where the acceleration is not varied for the variation in revolution, it is difficult to make conformity when the acceleration feeling is spoiled. 3) For example, a method of control cannot help being largely varied according to a mechanism such as the multiple-ratio geared transmission and a continuously variable transmission. In addition, it is difficult to apply the driving force control to a manual transmission mounted vehicle, an electric vehicle or hybrid vehicle.
It is, hence, an object of the present invention to provide driving force controlling apparatus and method for an automotive vehicle which can achieve compatibility between a large acceleration demand immediately after the acceleration start from the standstill and a vehicular velocity controllability in the vicinity to the target vehicular velocity after the target acceleration from the standstill and a vehicular velocity after the end of acceleration end and can achieve the compatibility between the large acceleration demand immediately after the overtake start at a time of the overtake acceleration and vehicular velocity controllability in the vicinity to the end of acceleration.
The above-described object can be achieved by providing an apparatus for controlling a driving force for an automotive vehicle, comprising: an accelerator manipulated variable detecting section that detects a manipulated variable of an accelerator; a vehicular velocity detecting section that detects a vehicular velocity; and a target driving force calculating section that derives a vehicular target driving force in accordance with a vehicle driver""s demand, the apparatus achieving the derived target driving force and the target driving force calculating section comprising: a vehicular velocity control purpose target driving force calculating section that calculates a vehicular velocity control purpose target driving force from an absolute value of the manipulated variable of the accelerator and the vehicular velocity; an acceleration control purpose target driving force calculating section that generates an acceleration control purpose target driving force from at least one of an absolute value of the accelerator manipulated variable and a variation speed of the manipulated variable of the accelerator; and a target driving force synthesizing section that synthesizes both of the vehicular velocity control purpose target driving force and the acceleration control purpose target driving force.
The above-described object can also be achieved by providing an apparatus for controlling a driving force for an automotive vehicle, comprising: an accelerator manipulated variable detecting section that detects a manipulated variable of an accelerator; a vehicular velocity detecting section that detects a vehicular velocity; and a target driving force calculating section that derives a vehicular target driving force in accordance with a vehicle driver""s demand, the apparatus achieving the derived target driving force and the target driving force calculating section comprising: a vehicular velocity control purpose target driving force calculating section that calculates a vehicular velocity control purpose target driving force from an absolute value of the manipulated variable of the accelerator and the vehicular velocity; an acceleration control purpose target driving force calculating section that generates an acceleration control purpose target driving force from at least one of an absolute value of a result of calculation by the vehicular velocity control purpose target driving force calculating section and a variation speed of the result of calculation by the same; and a target driving force synthesizing section that synthesizes both of the vehicular velocity control purpose target driving force and the acceleration control purpose target driving force.
The above-described object can also be achieved by providing a method for controlling a driving force for an automotive vehicle, the method comprising: detecting a manipulated variable of an accelerator; detecting a vehicular velocity; and deriving a vehicular target driving force in accordance with a vehicle driver""s demand, the method achieving the derived target driving force and driving the vehicular target driving force comprising: calculating a vehicular velocity control purpose target driving force from an absolute value of the manipulated variable of the accelerator and the vehicular velocity; generating an acceleration control purpose target driving force from at least one of an absolute value of the accelerator manipulated variable and a variation velocity of the manipulated variable of the accelerator; and synthesizing both of the vehicular velocity control purpose target driving force and the acceleration control purpose target driving force to achieve a target driving force of the vehicle.
The above-described object can also be achieved by providing a method for controlling a driving force for an automotive vehicle, the method comprising: detecting a manipulated variable of an accelerator; detecting a vehicular velocity; and deriving a vehicular target driving force in accordance with a vehicle driver""s demand, the method achieving the derived target driving force and deriving the target driving force comprising: calculating a vehicular velocity control purpose target driving force from an absolute value of the manipulated variable of the accelerator and the vehicular velocity; generating an acceleration control purpose target driving force from at least one of an absolute value of a result of calculation of the vehicular velocity control purpose target driving force and a variation velocity of the result of calculation of the same; and synthesizing both of the vehicular velocity control purpose target driving force and the acceleration control purpose target driving force.
This summary of the invention does not necessarily describe all necessary features so that the invention may also be a sub-combination of these described features.